2.14: PKCE Auth Flow

Added

• (experimental) Support to search multiple/all markets at once.
• Support to test whether the current user is following certain
  users or artists
• Proper replacements for all deprecated playlist endpoints
  (See https://developer.spotify.com/community/news/2018/06/12/changes-to-playlist-uris/ and below)
• Allow for OAuth 2.0 authorization by instructing the user to open the URL in a browser instead of opening the browser.
• Reason for 403 error in SpotifyException
• Support for the PKCE Auth Flow
• Support to advertise different language to Spotify
• Added 'collaborative' parameter to user_playlist_create method.
• Enforce CHANGELOG update on PR
• Adds additional_types parameter to retrieve currently playing podcast episode
• Support to get info about a single category

Deprecated

• user_playlist_change_details in favor of playlist_change_details
• user_playlist_unfollow in favor of current_user_unfollow_playlist
• user_playlist_add_tracks in favor of playlist_add_items
• user_playlist_replace_tracks in favor of playlist_replace_items
• user_playlist_reorder_tracks in favor of playlist_reorder_items
• user_playlist_remove_all_occurrences_of_tracks in favor of
  playlist_remove_all_occurrences_of_items
• user_playlist_remove_specific_occurrences_of_tracks in favor of
  playlist_remove_specific_occurrences_of_items
• user_playlist_follow_playlist in favor of
  current_user_follow_playlist
• user_playlist_is_following in favor of playlist_is_following
• playlist_tracks in favor of playlist_items

Fixed

• fixed issue where episode URIs were being converted to track URIs in playlist calls